Various forms of measuring devices have been in use for hundreds of years. The ruler, yardstick or meter stick is quite efficient and can accurately measure dimensions within reasonable accuracy limits. However, the major problem with these types of measuring devices is that they are cumbersome and hard to handle, carry or store.
Because of these common problems various ways have been tried to make a measuring device compact and easily handled and carried. The two most common devices that have evolved are the folding measuring ruler which is commonly used by carpenters and the convenient hand-held tape measure.
One of the attributes of the hand-held tape measure is that it is generally light weight and easily stored and used. The tape is compactly coiled within the housing and is spring biased to retract into the housing when not in use. This device provides an additional feature in that the tape as it is extended has a slightly concave cross-sectional bow which allows the tape to extend outwardly, in a self-supporting configuration for a substantial distance. In addition, another common feature of this type of device is that the length of the housing behind the extension point of the tape is usually a standard set dimension so that the device can be used for measuring inside dimensions by merely adding the set length of the case to the measurement shown on the tape face.
The primary drawback with this type of device is that only relatively coarse and inaccurate measurements can actually be made. These measurements are also limited to the units to which the tape is graduated. The accuracy of the readings depends upon how small these units are divided and how accurately they are interpreted by the user. Naturally, the size of the graduation will determine how well they can be seen, especially under poor lighting conditions.
The present invention is directed to a way of conveniently extending or retracting the tape from the housing and at the same time providing an extremely accurate and convenient measurement reading. This reading can even be obtained where there is only limited light. At the same time, the present invention can instantly convert the displayed measurement reading to fractional or decimal units of either the English or metric system. All of this can be done in a matter of a few seconds.